Nondestructive adult age at death estimation: Visualizing cementum annulations in a known age historical human assemblage using synchrotron X-ray microtomography

摘要

Objectives: Adult age at death estimation continues to challenge physical anthropologists. One estimation method involves counting tooth cementum annulations (TCA). Non-destructively accessing TCA is a critical step to approaching fossil teeth of unknown age and to verifying life history profiles of human ancestors. This pilot study aims to (a) non-destructively image TCA in teeth from a known age archeological human population by propagation phase contrast X-ray synchrotron μCT (PPCSR- μCT) (b) test the correlation between real and estimated ages, and the accuracy, precision and bias of age estimates. Materials and Methods: We examine 20 permanent human canines (aged 20-81 years), from a 18th to 19th century known age collection from St. Luke's Church (London, England).We scanned transverse segments of acellular cementum in the apical portion of the middle root third using PPCSR- μCT.We generated virtual transverse sections on which two observers perform two sessions of blind TCA counts.We calculate the estimated ages at death by adding 10 years to the TCA counts. Results: A moderately strong positive linear relationship exists between real and estimated ages (r = 0.76, p < .001), with an average inaccuracy of 16.1 years and an average bias towards underestimation of 15.7 years. This difference is lower in individuals <50 years (6.8 and 6.5 years, respectively, n = 10) compared with those >50 years (24.9 years, n = 10). Discussion: We reliably imaged and identified TCA in individuals <50 years from a known-age archeological sample. Scanning refinement will yield a promising alternative to current destructive methods of TCA analyses and to aid access to life history events in adult fossil hominins.